Moreover, his last words are kinda corny, but cast the first stone he who never simped for a cutie in his teens.
I've been thinking about this, also because a lot of people seem to dislike how Ryouko portrayed Kai in his last words. And once again I'll have to ask many of you to think with your brain, not with your heart; because his last words are quite accurate.
See Chapter 38, page 15; Chapter 51, page 19; and how things developed from Chapter 52 to 54. Indeed, he's a self-righteous lunatic, who wants to make this world a better place by killing every single bad person barring the way. But the real question which should be asked is, why? Why make this world a better place? For whom? So that no one out there ever becomes a victim again? Then what's the deal with killing schoolgirls (and let's not forget, all the delinquents that used to populate the school until they magically disappeared) instead of real bandits, robbers, drugdealers, rapists, serial killers? Because they're the most immediate threat to the one for whom he's devoting his ideals for: Sayoko.
He's most interested in making this world a better place so the one cutie he's been simping for years (successfully so, they even, gasp, held hands) doesn't suffer in anyone's hands, and he can't guarantee that by killing every wrongdoer out there because there are simply too many. A lesbian and potential sexual assaulter (Michiru), an uncaring bully (Miho), a chaotic self-destructing girl (Seo) are much closer to reach and much likelier to affect Sayoko.
I'm going to smack the next guy who calls this manga bad writing in both temples.